The present embodiments relate generally to advanced composites and, more particularly, to a system and method for rapidly fabricating advanced composite laminates with minimal scrap, using automated equipment.
Advanced composite materials are increasingly used in high-performance structural products that require low weight and high strength and/or stiffness. Composite materials are engineered materials that comprise two or more components. The embodiments relate to polymer composites that combine reinforcing fibers such as carbon fiber, glass fiber, or other reinforcing fibers with a thermosetting or thermoplastic polymer resin, such as epoxy, nylon, polyester, polypropylene, or other resins. The fibers typically provide the stiffness and strength along the direction of the fiber length, and the resin provides shape and toughness and also acts to transfer load between and among the fibers. The structural performance of an advanced composite part increases with increased fiber-to-resin ratio (also called fiber volume fraction), increased fiber length, closer alignment between the fiber orientation and the load path through the part (in contrast to random fiber orientation), and the straightness of the fibers. The weight of an advanced composite part can also be optimized by selectively adding or subtracting material according to where it is highly and lightly stressed.
Typically, the manufacture of high-performance, advanced composite parts is a slow and labor-intensive process. Thus, several approaches for automating the fabrication of advanced composite parts have been developed to reduce hand labor, decrease cycle time, and improve part quality and repeatability. Such machines are used to fabricate small and large parts ranging from aircraft fuselages and internal structural members to pressure vessels, pipes, blades for wind turbines, and wing skins. These machines typically place tape material directly on a mandrel or a mold using a material placement head mounted on a multi-axis, CNC manipulator. As the material is laid up, it is consolidated with any underlying layers. This is called “in situ” consolidation.
A different approach, described in U.S. Pat. Nos. 6,607,626 and 6,939,423, which are herein incorporated by reference, is to lay up a substantially flat “tailored blank” where all the plies of the composite laminate are only tacked together. Once the tailored blank has been made, subsequent processing steps are used to consolidate the plies together and form the blank into its final shape.
One characteristic typical to tape and fiber placement machines is the overall technique used to apply material to a tooling surface: such machines progressively unroll a tape or tow material onto a tooling surface that is configured to match the near net shape of the part and tack it in place using one or more compaction rollers or shoes as the material is fed onto the surface. While this technique yields high quality parts, one main limitation is that increasing the material placement rate requires larger, higher power machines, which has a compounding effect on system size, energy consumption, cost, and precision. In many systems, speed is also constrained by the heat transfer rate, especially for thermoplastic composites, which are typically melted and then refrozen during placement.
Another limitation of fiber placement and tape laying machines is that they most typically produce parts very near to the final net shape and thus the attainable part complexity and contour is governed by the size and dexterity of the manipulator to which the layup head is attached. Such systems typically require five or six degrees of freedom to produce the types of parts noted above.